He desarrollado un gráfico de barras con un motor gráfico, y he usado varias series que muestran barras de diferentes colores en función de la personalización realizada en los datos.

Pero cuando hay un valor nulo para una barra, XYmultiseriesrenderer aún representa el gráfico y crea espacios no deseados entre las barras.

private void openChart(){
            //int[] x = { 0,1,2,3,4,5,6,7,8,9};
            int[] income = { 230,220,230,250,270,300,280,350,370,400};
            int[] expense = {220, 270, 290, 280, 260, 300, 330, 340}; 
            int[] colors = {Color.GREEN,Color.YELLOW , Color.RED , Color.BLUE};

            XYSeries[] incomeSeries = addIncomeSeriestoDataSet(income);
            XYSeries expenseSeries = constructExpenseSeries(expense);
            // Creating a dataset to hold each series
            XYMultipleSeriesDataset dataset = new XYMultipleSeriesDataset();
            // Adding Income Series to the dataset
            for(int i= 0 ; i< incomeSeries.length ; i++) {
                dataset.addSeries(incomeSeries[i]);
            }
            //Adding Expense Series to the dataset
            dataset.addSeries(expenseSeries);

            // Creating a XYMultipleSeriesRenderer to customize the whole chart
            XYMultipleSeriesRenderer multiRenderer = buildRenderer(colors); 

            // Creating an intent to plot bar chart using dataset and multipleRenderer
            Intent intent = ChartFactory.getBarChartIntent(getBaseContext(), dataset, multiRenderer, 

    Type.DEFAULT);
      // Start Activity
            startActivity(intent);

        }private XYSeries[] addIncomeSeriestoDataSet(int[] income){
            XYSeries[] incomeSeries = {new XYSeries("Income<=250") , new XYSeries("Income<320") , new 

    XYSeries("Income>320")};
            // Adding data to Income series
            int i = 0;
            int sizeX = mMonth.length;
            int incomeItemsCount = income.length;

            while(i<sizeX && i<incomeItemsCount){
                if(income[i] <= 250) {
                    incomeSeries[0].add(i, income[i]);
                                } else if(income[i] <= 320) {

                    incomeSeries[1].add(i, income[i]);

                } else {

                incomeSeries[2].add(i, income[i]);
                }
               i++;
            }
            return incomeSeries;
        }

        private XYSeries constructExpenseSeries(int[] expense) {
            XYSeries expenseSeries = new XYSeries("Expense");
               int i=0;
               int sizeX = mMonth.length;
               int expenseItemsCount = expense.length;
               while(i<sizeX && i< expenseItemsCount) {
                    expenseSeries.add(i,expense[i]);
                    i++;
                }
              return expenseSeries; 
        }
        private XYMultipleSeriesRenderer buildRenderer(int[] colors) {
            XYMultipleSeriesRenderer renderer = new XYMultipleSeriesRenderer();
            renderer.setAxisTitleTextSize(16);
            renderer.setChartTitleTextSize(20);
            renderer.setLabelsTextSize(15);
            renderer.setLegendTextSize(15);
            renderer.setXLabels(0);
            renderer.setAxesColor(Color.BLUE);

            renderer.setXLabelsColor(Color.BLUE);
            renderer.setYLabelsColor(0,Color.BLUE);

            renderer.setXLabelsAlign(Align.CENTER);
            renderer.setChartTitle("Income vs Expense Chart");
            renderer.setXTitle("Year 2012");
            renderer.setYLabelsAlign(Align.RIGHT);
            renderer.setLabelsColor(Color.BLUE);
            renderer.setYTitle("Amount in Dollars");
            renderer.setBarSpacing(1.0);
            renderer.setMarginsColor(Color.WHITE);
            renderer.setApplyBackgroundColor(true);
            renderer.setBackgroundColor(Color.WHITE);
            renderer.setMargins(new int[] { 20, 30, 15, 0 });
            renderer.setZoomButtonsVisible(true);
            for(int i=0; i< mMonth.length ;i++){
                renderer.addXTextLabel(i, mMonth[i]);
            }
            int length = colors.length;
            for (int i = 0; i < length; i++) {
                XYSeriesRenderer r = new XYSeriesRenderer();
                r.setColor(colors[i]);
                r.setLineWidth(4);
                r.setFillPoints(true);
                r.setDisplayChartValues(true);
                renderer.addSeriesRenderer(r);
            }
            return renderer;